AP05 - respiratory neurology Flashcards
What do the anterior rami of the thorax bridge into?
muscular branch branches to parietal pleura lateral cutaneous branch intercostal nerve anterior cutaneous branch
How do carotid bodies detect CO2?
diffuses into cell, increaseing carbonic acid concentration, and hence protons
this reduces K+ content, depolarising the cell.
Ca2+ enters, and the glomus cells are excited, releasing neurotransmitter
What other state would mimic the same effect of high CO2?
acidosis inhibits acid-base transporters, changing proton concentrations ultimately have the same effect
What do chemoreceptors send messages to?
the medulla
What might damage to T2-T5 cause?
inhibition of mucus secretion in the trachea
inhibits control of tracheal smooth muscle, bridging the gap between the free end of the C-chaped cartilages
What is the carina of the trachea sensitive to?
light touch
Where is the trachea carina?
base of trachea at the separation into left and right bronchi
What is afferent pathway of the cough reflex?
sensory fibres in ciliated epithelium of upper airway and cardiac and oesophageal branches from diaphragm go to medulla via the Vagus nerve
What is the central pathway of the cough reflex?
coordination centre for coughing in the Pons and medulla oblongata, likely to overlap with respiratory nuclei
initially in the solitary nucleus, and then others, like the pre-Botzinger complex
the caudal medullary raphe nuclei (obscurus and magnus) are essential
What is the efferent pathway of the cough reflex?
to diaphragm via vagus, phrenic, and spinal motor nerves
to the intercostal muscles via phrenic and motor nerves
to the larynx from the nucleus ambiguus via laryngeal branches of the vagus nerve
How can you identify vagal afferent terminations?
their conductance speed
A fibre >3m/s
C fibre <2m/s
What is the structure of each neurovascular bundles for the ribs?
rib costal groove
vein
artery
nerve
How would you test for intercostal nerve damage?
press intercostal area and take a deep breath, positive test with pain
What might cause Phrenic nerve damage other than trauma?
up to 10% of cases are during operation, in heart or abdominal surgery
What is the valsalva manourvre?
forcefull exhalation when the mouth and nose are shut, it can be used as a test of autonomic control of the heart
What is the physiological response to the valsalva manouvre?
initial pressure rise
reduced nervous return and compensation
pressure release
return of cardiac output
What accounts for the initial increase in pressure during the valsalva manouvre?
blood is forced from pulmonary circulation into the left atrium, causing a mild rise in stroke volume
What accounts for the reduced venous return and compensation in the valsalva manouvre?
return of the venous blood to the heart is impeded by the pressure in the chest, heart output falls
What accounts for the pressure release in the valsalva manouvre?
pulmonary vessels and aorta re-expand
venous blood can then enter the chest and heart, cardiac output begins to increase
What might the valsalva manouvre be used to diagnose?
if with headache - arnold-chiari malformation
along with a echocardiogram it can be used to diagnose heart abnormalities (like in episodes of supraventrivular tachycardia)
Name 3 causes of diaphragmatic paralysis
mechanical trauma
compression
neuropathies (such as from diabetes)
What does diaphragmatic paralysis cause?
paradoxical movement, affected side moves upwards during inspiration
How might a unilateral diaphragmatic paralysis present?
usually aymptomatic and is often found incidentally on CXR
What is the pulmonary plexus and its’ relationship to the cardiac and oseophageal plexus?
it is the convergence of autonomic fibres supplying the lung
inferior to cardiac plexus
anteriorinferior to oesophageal plexus
What does the pulmonary plexus receive innervation from?
left and right vagus nerves
sympathetics from rami of superior 4 thoracic ganglia
What muscles are involved in quiet inspiration?
diaphragm levatores costarum serratus posterior superior external intercostals
What muscles are involved in quiet expiration?
serratus posterior inferior
internal intercostals
diaphragm (passive recoil)
